1. Field of the Invention
The present invention relates to a method of manufacturing a solid electrolytic capacitor and particularly to a method of manufacturing a solid electrolytic capacitor including an anode element made of a sintered body.
2. Description of the Related Art
In order to achieve reduction in size and increase in capacity of a capacitor, various capacitors have conventionally been developed. Among others, a solid electrolytic capacitor has widely been known as a capacitor suitable for reduction in size. A solid electrolytic capacitor includes an anode element, a dielectric film provided on the anode element, and a solid electrolytic layer provided on the dielectric film, and it has such excellent performance as a large capacity in spite of its small size.
A solid electrolytic capacitor including as an anode element, a sintered body obtained by sintering powders of a valve metal represents one of the solid electrolytic capacitors above. Since such a solid electrolytic capacitor includes a porous anode element, it can particularly have such excellent characteristics as a large capacity in spite of its small size.
Currently, in order to further improve the characteristics of the solid electrolytic capacitor including the anode element made of the sintered body above, technological developments have been promoted. For example, Japanese Patent Laying-Open No. 10-149955 describes thinly shaving a surface of an anode element through electrical discharge machining in order to eliminate clogging in the surface of the anode element. In addition, for example, Japanese Patent Laying-Open No. 2009-177174 describes etching of a surface of an anode element with an organic acid in order to remove a natural oxide film on the surface of the anode element.
Further, a technique for decreasing a particle size of powders of a valve metal, which is a source material for an anode element, has also been developed. By decreasing a particle size of powders, a surface area of the anode element can further be increased and hence a surface area of a dielectric film can further be increased. Therefore, significant increase in capacity can be achieved. Such an anode element as fabricated with powders small in particle size has attracted attention as a high-CV anode element having a CV value not lower than 100,000 μFV/g.